http://www.sciencedirect.com/science/article/pii/S1875510020300081 Reservoir characterization of thermogenic gas hydrates have so far been limited to seismic mapping, well log interpretation, and lab scale experiments, with numerical modeling mostly focusing on gas production from hydrates. What is unknown however is the hydrate saturation at the sub-seismic and interwell scales. This study uses numerical simulations for predictive modeling of hydrate formation and geobody distribution using TOUGH + Hydrate. Results indicate that the flow of gas is buoyancy and advection dominated, and affects hydrate formation rate and saturation distribution. Geological controls such as fault angles, stratigraphic thickness, permeabilities and permeability anisotropies and contrasts with adjacent formations significantly impact distribution of hydrate saturation, and geobody shape. Hydrates form in both high and low porosity rocks. While full-scale reservoir modeling is contingent upon the availability of detailed reservoir and fluid data, this study underscores the importance of using numerical modeling tools for quantitative predictive modeling and reservoir characterization of hydrate reservoirs for better resource estimation, well-placement decisions, reservoir management and production planning.

Dijkstra, N., Junttila, J., Aagaard-Sørensen, S., 2020. Impact of drill cutting releases on benthic foraminifera at three exploration wells drilled between 1992 and 2012 in the SW Barents Sea, Norway. Marine Pollution Bulletin 150, 110784.

http://www.sciencedirect.com/science/article/pii/S0025326X19309403 The aim of this study is to identify the environmental impact of drill cuttings (DC) released around three wells drilled in 1992, 2000 and 2012 in the SW Barents Sea. Foraminiferal assemblages are studied in cores taken along transects <250 mfrom wells. Well E-1992 shows no impact of DC on foraminifera indicating that low amounts of released DC limit environmental impact. Impact at wells G-2000 and S-2012, is confined to <30 m, and attributable to smothering of fauna, resulting in low foraminiferal density. We therefore argue that previous monitoring studies, mainly focusing on samples collected >250 mfrom wellheads, might not capture the full impact of DC. In well G-2000, a recovery layer indicates partial recovery 15 years after DC releases. In well S- 2012, no recovery is observed, 3 years after release. Released DC did not result in faunal composition changes.

Ding, W., Hou, D., Jiang, L., Jiang, Y., Wu, P., 2020. High abundance of carotanes in the brackish-saline lacustrine sediments: A possible cyanobacteria source? International Journal of Coal Geology 219, 103373.

http://www.sciencedirect.com/science/article/pii/S0166516219309000 The organic-rich oil shales of low maturity and tight oils from the Middle Permian Lucaogou Formation were formed in a brackish-saline lacustrine environment in the Jimusaer Sag, Junggar Basin. They are characterized by remarkably abundant β - carotane and γ -carotane. The biological sources and favourable sedimentary environments of carotanes formation remain obscure. Organic geochemical analyses of 17 oil shales and 20 tight oils from the Jimusaer Sag reveal that reducing, evaporitic and carbonate-rich, shallow water environment is favourable for β -carotane accumulation. Geochemical studies show that carotane abundance is controlled by both source of organic matter and sedimentary environment rather than thermal maturity in the study area. Even though both higher plants and microalgae are reported to be precursors of carotanes, cyanobacteria may be the main biological sources of carotanes in the Lucaogou Formation based on cyanobacteria-derived biomarkers, such as the C 2,6-dimethyl benzene-substituted isopr enoid, 2α -methylhopanes, 7- and 8- 39 monomethylhepadecanes. The airborne volcanic ash containing ample elements (e.g. Mgand Fe) caused by the intermittent volcanic eruptions during the Middle Permian most likely contributed to the flourish of cyanobacteria in the study area.

Dix, B., de Bruin, J., Roosenbrand, E., Vlemmix, T., Francoeur, C., Gorchov-Negron, A., McDonald, B., Zhizhin, M., Elvidge, C., Veefkind, P., Levelt, P., de Gouw, J., 2020. Nitrogen oxide emissions from U.S. Oil and gas production: Recent trends and source attribution. Geophysical Research Letters 47, e2019GL085866.

https://doi.org/10.1029/2019GL085866